Commonly owned U.S. Pat. Nos. 3,767,352 and 3,807,915 disclose injection-molding machines in which a stripper plate is sandwiched between coacting mold portions in a mold-closed position and during the mold-opening stroke is gradually separated from one of these mold portions by an articulated linkage connected with the relatively movable mold portions or their supporting platens. U.S. Pat. No. 3,767,352 also shows a stack mold with two pairs of coacting mold portions and two interposed stripper plates movable symmetrically on opposite sides of the intermediate mold portions.